he pounts out a magnitude ten earthquake would release 32 times more energy than the nine tremor that struck northeastern japan last year. the woshld's largest known earthquake hit chile in 1960 with a magnitude of 9.5. the seismologist said that would occur only under particular circumstances. for example, the fault that spans 8,800 kilometers along the northern pacific rim trench would have to shift by 20 meters. >> i'm not saying a magnitude ten earthquake will definitely occur, but people should be aware of what could happen. >> he says such an earthquake would result in tremors lasting 20 minutes to an hour and triggered tsunami for several days. >>> experts have been predicting another large quake will strike japan. one area at risk is the southern coast. officials as many as 320,000 people in the region could die. they say a major tremor could strike wakayama especially hard, killing up to 80,000 people. >>> nhk world took a look at how residents of one town are trying to prepare. >> reporter: if there's a major earthquake, people will have to head to higher ground no matter wh